I would really prefer any location sharing feature to be something that ran on top of the communication platform rather than be a feature baked into the app. Create a generic information syncing mechanism for groups and let clients build features like location sharing on top of that. Location sharing seems so niche that bundling it into the client encourages poor opsec/privacy behavior.

As I have heard, Telegram is unencrypted by default. Both WhatsApp and Telegram are poor at making this 100% clear 100% of the time despite privacy being a major purpose of the apps. I'll admit I really haven't used telegram much but WhatsApp encourages backing up chats to cloud storage. WhatsApp also only provides a single alert that a contact's security code has changed. It also doesn't encourage verifying the security code on the initial contact. i.e if someone out of the blue contacts you on WhatsApp the only security is the phone number.